In the known art, there has been proposed “an automatic cooling/heating switching system included in an air-conditioning system in which a certain outdoor unit is connected to a plurality of indoor units with one refrigerant piping system, the automatic cooling/heating switching system comprising a temperature control means that detects and controls ambient temperatures of each of the indoor units, a controlling means that determines an operation mode of the air-conditioning system by integrating each operating state of the indoor units each defined in correspondence with a difference between the ambient temperature related to the indoor unit and set temperature related to the indoor unit, and an operation mode switching means that switches all the indoor units to cooling or heating operation at a time on the basis of the determination” (see Patent Literature 1, for example).